JP2011526550A - Molded product having hook surface obtained by injection molding - Google Patents

Abstract

  A body (20), obtained by injection molding at at least one injection point, having a volume defined by a space in the plane forming the outer envelope surface, the same as the body of the molded article At least one hook (21) obtained at the time of molding, preferably comprising a hook plexus, said hook or each hook having a post having a longitudinal axis and a catching part protruding laterally from the post, the volume of the hook Is substantially less than the volume of the body, ie, at least as small as 1 / 100th of the volume of the body, preferably as small as 1 / 1,000, for example, as small as 100,000 to 100,000,000. The strut width measured transversely to the longitudinal axis, or the minimum transverse dimension, is less than the thickness of the body measured along the longitudinal axis of the strut Providing a molded article which is characterized that no.

Description

  The present invention relates to a one-piece molded article obtained by injection molding from at least one injection point and having a body with a volume defined by a space inside the outer surface, an example of the molded article being the interior of an automobile Door panels.

  The invention also forms an apparatus for forming an injection mold designed to form a molded article of the type described above by injection molding, as well as a mold insert designed to be inserted into a mold of the aforementioned type. Regarding blocks.

  Molded articles of the above type are known in the prior art.

Its purpose is to add at least one hook, preferably a hook plexus, to the outer surface of the molded part,
1) The at least one hook, preferably the hook plexus, is obtained by the same molding steps as the body and is integral with the body;
2) The at least one hook, preferably the hook plexus, is such that the volume of the hook is substantially smaller than the volume of the body, i.e. at least one hundredth smaller than the volume of the body, preferably one thousandth. Small, for example as small as 100,000 to 100,000,000,
3) The at least one hook, preferably the hook of the hook plexus, is thin, i.e. shaped at the base level, where the smallest transverse dimension at the base level is measured along a straight line perpendicular to the plane. Less than product thickness.

  The hook or each hook is a hook and loop, or a hook in the hook, for example to cooperate with the loop or hook of this other item, in order to fix the molding to another item Designed to form the male part of the self-gripping mechanism.

  In the present application, the hook means an element including a support column and a capture portion protruding laterally from the support column, and specifically includes a hook shape, a double hook shape, a mushroom shape, and the like.

  Until now, in the prior art, as specifically described in European Patent No. 0,577,697, a thin plate, a thick hook, In particular, it has already been possible to form a hooked plate with a hook having a width greater than the thickness of the plate. However, with the method described there, it is impossible to obtain a hook with a very small width dimension of the column.

  In EP 0,577,697, injection molding is used to mold the hook plexus designed to cooperate with the loop into the outer surface of the molded product (orthopedic knee pad) with the same mold. Has been. Conventionally, a hollow plexus having a shape substantially complementary to a hook to be manufactured has been provided on a part of the inner surface of the mold. The cavity plexus is placed in a suitable position to form the hook at the exact location where the final molded article hook should be formed. Next, a molding material, which is specifically a thermoplastic material and fills the inner space of the mold and also the molding cavity of the hook, is injected into the mold, thereby forming an integral part of the outer surface of the molded article. A molded product with a hook plexus is obtained.

  However, with this mold and this method, it is impossible to produce a molded article having a hook having a small volume and / or width.

  In fact, the dimension of the cavity for forming the hook is small compared to the volume of the final molded product, so that the injection pressure of the thermoplastic material is not sufficient to effectively allow the thermoplastic material to enter the cavity. There is.

  Overmolding based system that improves the quality of filling cavities of cavities with thermoplastic material and makes it possible to obtain hooks having a height and width smaller than the thickness of the molded part at the hook level Is already known in the prior art, specifically US Pat. No. 6,224,364. However, the technique proposed in this prior document has several drawbacks. First, the final product obtained is not a one-piece, but two-piece piece overmolded with each other, separated by an interface within the molded material itself, which interface the hook with the rest of the molded product. Is divided from the majority of. On the other hand, this interface causes the molded product to be vulnerable, which is detrimental to the useful life of the molded product. In fact, this interface may eventually form areas with reduced resistance to hook tension, resulting in rapid degradation of the molded part, and in particular, may cause the hook plexus area to delaminate from the molded part. Thereby making it impossible to use the part in cooperation with another part having a loop or hook to which it is to be fixed. Furthermore, the apparatus for forming the mold is complex in structure, so that it provides a plurality of openings for injecting material, in particular an injection opening facing the cavity plexus forming the hook, It is essential to have a movable part with respect to the other parts, and that movable part causes both design and use difficulties, especially with respect to sealing and long-term reliability. Furthermore, once the mold is constructed, it is difficult to change the position of the cavity plexes anywhere in the mold, and the mold must be completely recreated. The above-described method also has the disadvantage of being in two stages, thereby increasing the production time of the final molded product.

According to the present invention, a body which is an integral part and is obtained by injection molding at at least one injection point, the body having a volume defined by an in-plane space forming an outer envelope surface; Having at least one hook, preferably a hook plexus, obtained at the same molding as the body of the molded article, said hook or each hook having a post having a longitudinal axis and a catching part projecting laterally from the post In
The volume of the hook is substantially smaller than the volume of the main body, i.e. at least one hundredth smaller than the volume of the main body, preferably smaller than one thousandth, e.g. 100,000 to 100,000,000 minutes. As small as 1,
For the first time, it is possible to obtain a molded product characterized in that the strut width measured transversely to the longitudinal axis, or the smallest transverse dimension, is smaller than the thickness of the body measured along the longitudinal axis of the strut Became.

  Preferably, the maximum height dimension of the hook or each hook measured along the longitudinal direction is less than the thickness of the body measured along the longitudinal axis of the column.

  Preferably, the hook plexus covers only a small part of the outer surface, which specifically is strictly less than 1/2 of this outer surface, preferably less than 30%.

  Preferably, the width of the base of the column is less than 0.29 mm, specifically 0.05 to 0.15 mm.

  In order to obtain this type of molded article, according to another aspect of the present invention, an apparatus for forming a mold for molding a molded article by injecting a molding material, specifically a thermoplastic material. A closed inner surface defining a main molding chamber, at least one opening for introducing molding material to be molded, so that the molding material can be introduced into the molding chamber by injection, Comprising at least one cavity complementary to at least one hook, preferably a cavity plexus, which is open to a part, wherein said part of the inner surface is surrounded by an edge surface without a cavity, Means for pressing at least a portion of the edge surface and the opposite portion of the inner surface toward each other are disposed, and the two surfaces pressed toward each other are completely Without having to touch, in particular it is possible to use the apparatus characterized always said that the arrangement is adapted to be restricted to a gap exists between the two surfaces.

  The present invention forms a mold having a simple structure, in particular, a final mold comprising a hook integral with the molded article, which may only require a single opening to inject the thermoplastic material. The hook plexus can be placed at virtually any position on the outer surface of the molded article, making it possible to obtain a truly integral molded article and hook plexus, specifically Overcomes the drawbacks of prior art devices by proposing a device in which the hook has a small dimension with respect to the body of the molded product without including an interface between the main part of the molded product and the hook plexus. .

  In known systems of the type described in U.S. Pat. No. 6,224,364, a thermoplastic material intended to form a hook does not penetrate the cavity in a more effective manner than conventional systems. There is no assistance, where the cavities forming the hooks are only arranged so that the hooks are formed at the end of the filling of the forming cavities. Specifically, the inventors of the present invention have noticed that a phenomenon occurs that can be classified as wrinkles. The phenomenon consists of “spoofing” the material entering the cavity to form a hook, and then forming a kind of membrane that shields the cavity opening and prevents the material from entering the cavity. As a result, when the molded product is pulled out of the mold, the molded product has no hooks or more hooks are missing from the plexus than the number of cavities. On the other hand, according to the present invention, the thermoplasticity is ensured by ensuring that the pressurization of introducing the thermoplastic material into the cavity forming the hook is very large, very rapid, in particular faster than the systems known in the art. Even if the material and the hook cavity have the same shape, the penetration of the material into the cavity is improved. This rapid increase in pressure has the effect of increasing the rate at which material arrives in front of the cavity opening, which results in preventing the formation of films as occurs in the prior art, and as a result A hook having a relatively small volume can be obtained.

  According to a preferred embodiment, the main molding chamber has a shape that is substantially complementary to the molded part to be molded.

  Preferably, the gap has a very small dimension, specifically 0.01 to 0.1 mm.

  According to the present invention, this gap is measured in the vertical direction of these two surfaces where the one surface portion and its opposing surface meet at one or more points farthest apart.

  In particular, this gap or play is much smaller than the depth of the cavity having a shape complementary to the hook, specifically at least as small as tenths, preferably at least as small as one hundredth. small.

  As described above, according to the present invention, it is not necessary to provide an opening that opens on the facing surface in order to form the portion having the hook after most of the molded product is formed. Specifically, it is possible to introduce a thermoplastic molding material through a single opening, and this thermoplastic material is mainly used except for the gap between the surface having the hook and the opposite surface. Since the entire chamber is filled and the size of the gap is actually chosen to be very small, a pressure corresponding to the pressure prevailing when substantially the entire chamber is filled with molding material is applied to the thermoplastic material. Unless added, the thermoplastic material cannot enter the gap, and only when the majority of the chamber (ie, other than the gap) is filled and the pressure of the thermoplastic material increases, the force generated by the pressing means While opposing, the thermoplastic material can penetrate the gap. As soon as the material begins to penetrate the gap, the force applied by the material is much greater than the pressing force. The space above the cavity is then suddenly opened, and then the material explosively fills that space as well as the cavity forming the hook under very high pressure and very high pressure.

  Since molding is performed in a single step that introduces or injects the thermoplastic material into the mold, most of the thermoplastic material is cooled to form the hook, as in the prior art. There is no need to mold the hook afterwards, so the molded product and the hook are uniform as a single piece without forming an interface in the base material between the hook plexus and the other parts of the molded product Formed. One of the unique features of the resulting product is that material enters through the entire periphery of the pressed area and collects in the central area according to a pattern that may be point, straight, or star shape, depending on the shape of the hook plexus That is. Due to the speed of the process, there is no time for the top of the material to cool down, so there is no true interface between the hook and the rest of the molded part (specifically, visible with the naked eye). There is no interface that can be)), so it does not form a highly fragile region in the part. Specifically, this region can be revealed only by analyzing the molecular orientation.

  Preferably, at least one opening, in particular the inlet opening (s) for injecting the thermoplastic material into the mold, in particular in a part of the inner surface other than the facing surface, is in the molding chamber. Open to.

  According to a preferred embodiment, the entire edge region is held away from the facing surface portion.

  According to a preferred embodiment, the edge region and the inner surface are continuous with each other and are held away from the opposing surface.

  According to another possible embodiment, the edge region is constituted by the shoulder of the inner surface part, only the edge part being held away from the opposing surface.

  According to another possible embodiment, the edge portion comprises a curved portion that contacts the opposing surface at its upper end, and the other portion of the edge region is held away from the opposing surface.

  According to a preferred embodiment, only a part of the edge region is kept away from the facing surface.

  According to a particularly preferred embodiment, an insert block is provided comprising a top surface formed with cavities or plexus having a shape complementary to the hook, the insert block being in a molded cavity, in particular a finished product. The hook is detachably disposed at a position where the hook is to be formed, the pressing means is integrated with the insert block, and the upper surface of the insert block constitutes the inner surface portion of the mold.

  Thus, in order to form the hook plexus at any location on the molded article, the insert block is placed where the hook is to be formed within the molding cavity without being constrained by the existing design of the mold.

  According to a preferred embodiment of the present invention, the pressing means comprises at least one spring. It is also possible to configure the pressing means with a hydraulic or air jack.

  The invention also relates to an insert block used in the molding device according to the invention.

  The present invention is also a method for producing a molded article comprising a hook or hook plexus obtained integrally with a portion of its outer surface by molding, comprising the steps of providing an apparatus of the present invention for forming a mold, And injecting thermoplastic material through the opening in the injecting step, in particular in the injecting step.

For example, when the car door panels, the ratio may exceed 10 ^5.

  Preferably, the hook has a size or height of less than 0.9 mm, specifically 0.2 mm to 0.7 mm.

  Specifically, the molded product is provided with at least one region on the outer surface thereof in the form of a depression or a dot corresponding to a location where material is injected when the molded product is manufactured by injection molding.

  Next, for the purpose of illustration, a preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of an apparatus for forming a mold according to the present invention. 2 is a perspective view of an insert block of the apparatus for forming the mold of FIG. FIG. 3 is a partially cutaway view of FIG. 4a, 4b, and 4c are schematic diagrams illustrating the progress of the molding process when the apparatus for forming the mold of FIGS. 1 to 3 is used, respectively. FIG. 5 is a view substantially equivalent to the view of FIG. 3 of another possible embodiment of a mold insert according to the invention. FIG. 6 is a diagram representing a curve showing the injection pressure of the thermoplastic material as a function of time during the molding process according to the invention. Figures 7a, 7b, 7c, 7d, 7e and 7f are schematic diagrams describing a plurality of possible arrangements according to the invention of the edge region, the surface in the cavity and the opposing surface. Figures 8a and 8b show another embodiment of the device according to the invention, in which parts having the same functions as the embodiments of the other figures have the same reference numbers. FIG. 9 is a cross-sectional view of the molded product obtained at the end of the molding step of FIG. 4a.

  FIG. 1 represents a mold consisting mainly of two parts 1 and 2, which close together to define a molding chamber 3 having the shape of the part to be molded. An opening 4 is formed in the upper part 1 for introduction by injection of a thermoplastic molding material. An insert block 5 is arranged in the molding chamber 3. The insert block 5 can be placed virtually anywhere within the cavity. However, the insert block 5 must never be placed opposite the opening 4.

  The insert block 5 can be seen better shown in FIGS. 2 and 3, but is substantially constituted by a right-angled parallelepiped, with an upper surface 6 on the hook to be formed on the outer surface of the molded product A plexus of cavities 12 having a complementary shape is formed. The insert block includes a parallelepiped base block 7 and a movable block 8. The block 7 is designed to be fixed (preferably removable) to the inner surface 9 of the chamber 3, while the block 8 is movable with respect to the block 7 and thus to the mold. But it is movable. A spring 10 is incorporated in the block 5 and presses the movable block 8 towards a part of the inner surface of the chamber, in particular the upper surface 6 of the movable block 8 with a cavity 12 having a shape complementary to the hook. Toward the portion 11 of the inner surface of the chamber that is substantially opposite the surface. The upper surface 6 of the movable block can be subdivided into two parts. A central portion 6 'defined by the outermost hook cavity and an edge 6 "surrounding the central portion 6'.

  Specifically, when the spring is unloaded, i.e., specifically when there is no pressure of the thermoplastic material injected into the cavity, the top surface 6 is at a short distance from the surface 11, specifically, It is adjusted so that a gap or play such as about 0.01 to 0.1 mm is formed. This play is such that the two faces 6 and 11 are not in full contact with each other, but the thermoplastic material cannot enter the play until the entire chamber other than the gap and cavity 12 is completely filled. It is like that. Specifically, the non-voided edge portion or region 6 ″ of the top surface 6 is spaced from the opposing surface portion 11.

  This play corresponds to 1/10 to 1/100 of the cavity depth of the mold (or the height of the hook) of the mold.

  Note that the upper surface 6 of the insert 5 has a smaller dimension relative to the inner surface 9, so that the insert is totally surrounded by the remaining space of the chamber 3.

  The usage of the apparatus for forming the mold is as follows. In order to form a molded product having a complementary shape in the chamber 3, a liquid thermoplastic material is injected through the opening 4. Initially, the thermoplastic material is introduced into the space that has the least resistance to its progression, that is, the thermoplastic material fills the entire chamber 3 except for the gap between the surface 11 and the surface 6. The gap is too small for the thermoplastic material to enter the gap on its own without pressure or at a pressure lower than that present when filling the entire chamber 3. When substantially all of the chamber 3 is filled, the introduction of the thermoplastic material is continued to increase the pressure of the thermoplastic material in the space occupied in the chamber 3, and then the thermoplastic material Under the action of pressure, it enters the gap between the two opposing hook surfaces (6 and 11), and the pressure is abrupt and material is rapidly introduced into this gap, and the insert 10 The block, specifically, the portable portion 8 is pressed. The presence of this spring and the small gap means that the pressure required to begin introducing the thermoplastic material is high. As a result, the penetration of the thermoplastic material into the gap occurs abruptly, almost in the same way as an explosion with great force and great kinetic energy, so that the thermoplastic material has a cavity 12 having a shape complementary to the hook. Is effectively introduced and the hook is "formed" well.

  After the hook is formed, the introduction of the thermoplastic material is stopped, the thermoplastic material is allowed to cool, and the half mold 1 is opened relative to the half mold 2 in order to remove the final molded product from the chamber 3. . The final molded product comprises on its upper surface hook plexus having a shape complementary to the mold cavity 12 in the upper surface 6 of the insert block 5. The hook plexus is integral with other parts of the molded product, and specifically, there is no interface that forms a division in the base material of the molded product.

  The molded product obtained at the end of the step of FIG. 4C is shown in FIG. The molded product is a plate-shaped main body 20 (excluding the hook), and protrudes from the plate and is integrated with the plate in an integrated product state. Specifically, the molded product is a hook 21 obtained from the same mold. Is provided. The height h of each hook is smaller than the thickness e of the plate in the direction perpendicular to the lower surface of the plate from which the hook projects. The two values are measured along the axis of each hook strut, which in this case is also perpendicular to the outer surface of the body 20. The width of the base of the column is smaller than the thickness e of the plate, measured on a plane perpendicular to the column axis. In addition, the hook plexus only covers a portion of the lower surface of the board, which covers less than 50% of the entire outer surface of the board. In this case, given that FIG. 9 is a cross-sectional view at the level of the hook, the hook plexus covers less than 30% of the board, and actually even less than 10%. The hook plexus extends only in the direction perpendicular to FIG. 9 with a relative dimension to the plate, and the relative dimension is equivalent to the relative dimension in which the hook plexus extends in the direction shown in the figure. The dimensions can be easily derived from the form of the insert 5 in FIG.

  According to the embodiment shown in FIG. 5, the upper edge region 6 ″ is curved. This curved portion cooperates with the opposing surface portion 11 to ensure that a kind of wedge is formed along the outer edge, which will allow the thermoplastic material to enter between the two faces 6 and 11. If so, it is possible to facilitate the entry of the thermoplastic material, even if the two faces are in contact with each other at the level of the central region 6 '. That said, the contact between the two surfaces is not perfect because the two surfaces are not in contact at the level of the outer edge region.

  Although not shown, according to another embodiment encompassed by the present invention, a cavity is formed in the inner surface 9, specifically a portion 11 of the surface, and the upper surface 6 is formed from a complete block (ie, without a cavity). It is also possible to do. In this type of embodiment, the advantage that the hook plexus can be placed anywhere in the final molded product is obviously not obtained, but one of the important effects of the present invention is obtained: A hook is formed by virtually instantaneous injection.

  In the embodiment schematically shown in FIG. 7 a, the edge region 6 ″ is configured as a shoulder with respect to the central region 6 ′, and the pressing means presses the surface 6 ′ to contact the opposing surface 11. However, the shoulder keeps the edge region 6 ″ spaced from the opposing surface.

  In the embodiment schematically shown in FIG. 7b, the edge region 6 '' comprises a curved part projecting with respect to the central region 6 ', and the pressing means has an upper end of the curved part of the region 6' '. Press to bring it into contact with the opposing surface 11. However, the inclined portion of the curved portion outside the central region 6 'is spaced from the opposing surface, so that the thermoplastic material enters when the pressure is sufficiently opposed to the force of the pressing means. And generate a wedge that can enter.

  In the embodiment schematically shown in FIG. 7 c, two protrusions 30 protrude from the surface of the central region 6 ′, and the pressing means presses these protrusions into contact with the opposing surface 11, but the rest of the surface 6 The part, specifically the edge region 6 '', is kept spaced from the facing surface.

  In the embodiment schematically shown in FIG. 7d, only the edge area 6 '' is pressed by the pressing means, the central hook area 6 'is fixed with respect to the facing surface and spaced apart from it. Yes. The pressing means pushes the region 6 ″ (surrounding the central region 6 ′) toward the facing surface, but keeps the region 6 ″ spaced from the facing surface. When the pressure of the molding material comes to fully counteract the force of the pressing means, the region 6 "moves away from the facing surface and the material can penetrate into the central region 6 '.

  In the embodiment schematically shown in FIG. 7e or 7f, the edge region 6 '' has an eccentric part. The pressing means presses the upper surface 6 (configured by the central region 6 ′ and the eccentric edge region 6 ″) toward the opposing surface. However, the pressing force is limited so that the eccentric part remains separated from the opposing surface by a small gap, and the other part of the surface 6 contacts the opposing surface.

  FIG. 6 schematically shows the shape taken by the curve giving the injection pressure of the thermoplastic material as a function of time during the production of the molded part. In the first time interval I, the pressure rises in a normal increasing manner, corresponding to filling the chamber volume excluding the gap and the hook cavity. After interval I, the pressure increases more rapidly during interval II until pressure Pmax is reached. During a very short interval III, filling of the gaps and cavities takes place, the injection pressure decreases slightly and then increases again. According to the invention, the injection is performed continuously and in a single step.

  Figures 8a and 8b show another embodiment of the molding apparatus according to the invention.

  As can be seen in FIG. 8 a, the insert block 5 comprises two sub-blocks 51 and 52. The upper block 51 defines therein a receiving portion 53 that opens on the lower side opposite to the upper surface 6 and receives the sub-block 52. The sub-block 52 is formed with two lateral recesses 54 that open into the sides of the sub-block 52, and the recesses 54 receive two springs 55, respectively. The spring is provided with a protrusion 56 at its free end. Two depressions 57 having a shape substantially complementary to the protrusion 56 are formed on the inner side wall of the sub block 51.

  In the position shown in FIG. 8a, the upper surface 6 is spaced from the surface 11 of the mold. The protrusion 56 pressed by the spring 55 protrudes from the recess 54 and at least partially fits into the recess 57, so that the two sub-blocks become integral with each other. Starting from this position shown in FIG. 8a, a thermoplastic material is introduced into the mold. When the material pressure is sufficient, the sub-block 51 is pushed down and at the same time the protrusion is pushed into the recess 54 so that the sub-blocks 51 and 52 are released from each other and move to the position shown in FIG. 8b. As a result, a large gap is created between the surfaces 11 and 6 so that the cavity 12 can be filled. When the part is cooled, the ejector 58 pushes the part out of the mold and the traction of the molded hook fully returns the two sub-blocks to the position of FIG. 8a.

  In the present invention, the top surface of the insert block (having reference numeral 6 in the drawing) means all points on the outer surface of the block that are visible when the insert block is viewed from above in the vertical direction. Also, the central part (with reference numeral 6 'in the drawing) means the central part of the top surface, in which all of the cavities designed to form the hooks open, Determined by the outermost point of the outermost edge of the cavity opening at the outermost of the cavity and by a straight line connecting these points together, so that the closed curve thus obtained is Including all cavities. Finally, the edge portion (having reference numeral 6 ″ in the drawing) is the upper surface portion outside the curve that defines the central portion. The edge portion surrounds the central portion.

Claims (16)

A body (20) which is an integral part and is obtained by injection molding at at least one injection point, the body (20) having a volume defined by a space in the plane forming the outer envelope surface, and said molded part Comprising at least one hook (21), preferably a hook plexus, obtained at the same time as the body of the body, wherein the hook or each hook has a longitudinal axis and a hook-like shape projecting laterally from the pillar In what has a part,
The volume of the hook is substantially smaller than the volume of the main body, i.e. at least one hundredth smaller than the volume of the main body, preferably smaller than one thousandth, e.g. 100,000 to 100,000. As small as 1 / 1,000,
Molded article characterized in that the strut width or transverse minimum dimension measured transverse to the longitudinal axis is less than the thickness of the body measured along the longitudinal axis of the strut.   Molded article according to claim 1, characterized in that the hook plexus covers a small part of the outer surface, i.e. strictly less than 1/2 of this outer surface, preferably less than 30%.   The maximum height dimension of the hook or each hook measured along the longitudinal axis is less than the thickness of the body measured along the longitudinal axis of the struts, or 2. The molded product according to 2.   The width of the base of the support, that is, the minimum dimension of the base of the support in the direction transverse to the longitudinal axis is less than 0.29 mm, specifically 0.05 to 0.15 mm. The molded article according to claim 1, 2, or 3.   The molded article according to any one of claims 1 to 4, wherein the hook has a size or height of less than 0.9 mm, specifically 0.2 mm to 0.7 mm.   The said molded article is provided with at least one area | region of the form of the hollow or point corresponding to the location into which material is inject | poured when manufacturing a molded article by injection molding on the outer surface. The molded product according to any one of the above.   An apparatus for forming a mold for molding a molded article according to any one of claims 1 to 6 by injection of a molding material, specifically a thermoplastic material, comprising a main molding chamber. A closed inner surface defining, and at least one opening for introducing the molding material to be molded, in particular to allow the molding material to be introduced into the molding chamber by injection; Comprising at least one cavity, preferably a cavity plexus, of a shape complementary to at least one hook that opens into a part (6 ') of the inner surface, said part (6') of said inner surface not comprising a cavity In the area surrounded by the edge surface (6 ″), means for pressing at least a part of the edge surface (6 ″) and the opposing portion (11) of the inner surface are arranged. The arrangement is made so that the pressing by the pressing means is limited so that the two surfaces (6 ″) and (11) pressed toward each other do not completely come into contact with each other. A device characterized by.   8. Device according to claim 7, characterized in that there is always a gap between the two surfaces.   The gap has a very small dimension, specifically 0.01 to 0.1 mm, and the gap is one or more points where the one surface portion and its opposite surface are farthest apart. 9. The device according to claim 8, characterized in that it is measured in the direction perpendicular to the two surfaces facing each other.   This gap or play is much smaller than the depth of the cavity having a shape complementary to the hook, specifically at least as small as 1/10, preferably as small as at least 1/100. Device according to any one of claims 7 to 9, characterized in that   At least one opening, specifically the introduction opening, specifically an opening for injecting a thermoplastic material into the mold, and opening into the molding chamber at a part of the inner surface other than the opposing surface. Device according to any one of claims 7 to 10, characterized.   An insert block having a top surface formed with cavities or cavities having a shape complementary to the hook is provided, and the insert block is formed in the molding cavity, specifically, the hook of the finished product is formed. The detachable arrangement at a power position, the pressing means is incorporated in the insert block, and the upper surface of the insert block constitutes the inner surface portion of the mold. The apparatus as described in any one of 7-11.   Device according to any one of claims 7 to 12, characterized in that the pressing means comprise at least one spring.   14. A device according to any one of claims 7 to 13, characterized in that the pressing means comprise a hydraulic or air jack.   An insert block having an upper surface formed with cavities or plexus having a shape complementary to the hook, and removably disposed in the molding cavity, specifically, at a position where the hook of the finished product is to be formed. An insert block in which the pressing means is incorporated and the upper surface constitutes the inner surface portion of the mold.   A method for producing a molded article comprising a hook or hook plexus integral with a part of its outer surface by molding, comprising the step of providing an apparatus for forming a mold according to any one of claims 7-14. And injecting the thermoplastic material through the opening in a single introduction step, specifically an injection step.

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